SEOUL - A former key aide to South Korean President Lee Myung-bak was summoned Wednesday for questioning on allegations he was involved in a vote-buying scandal in 2008.

Kim Hyo-jae, who stepped down last week as the senior presidential secretary for political affairs over the allegations, is suspected of having attempted to bribe lawmakers ahead of the ruling party's 2008 leadership contest when he served as a secretary for Park Hee-tae, a six-term lawmaker.

Kim Hyo-jae (C), former chief political-affairs secretary of South Korean President Lee Myung-bak, arrives surrounded by reporters at the central prosecutors' office in Seoul February 15, 2012.[Photo/Agencies]

That year, Park was elected head of the conservative ruling Grand National Party, currently the Saenuriy Party, and held the post for two years before becoming a parliamentary speaker.

He was pressured out of office last week, while skating around the bribery accusations.

The scandal, brought to light by a ruling party lawmaker who claimed he received a cash envelop before the 2008 race, has been a blow to President Lee Myung-bak's ruling party as it struggles to recover from a series of recent election defeats and other scandals ahead of key polls this year.

A series of scandals implicating Lee's relatives and aides have surfaced in recent months, prompting the beleaguered ruling party to draw up reform measures in a bid to distance itself from the Lee administration before the polls.